The process of mass-producing containers that contain liquid includes far more than simply placing a container under a spigot and allowing liquid to flow into it. In known filling systems, the container must be purged of any ambient air. This is because oxygen in the air may be detrimental to long-term storage of the beverage. In some cases, depending on the nature of the container, the container must be pre-tensioned before filling. Finally, during the filling itself, the incoming liquid displaces whatever gas happens to be in a container. Thus, there must be some way to dispose of this gas while the liquid actually flows into the container. Finally, the filling element must place the correct amount of liquid in each container.
A filling element must therefore be able to do more than just turn a spigot on and off. It must manage the various gas flows that are required during filling. These gas flows have different requirements. Known filling elements face difficulty in controlling these sometimes contradictory demands without considerable complexity.
Additionally, the various gases that are used during this process are not without cost. Known filling elements tend to behave as if this were not the case. As a result, copious amounts of various process gases are used up. This drives up the cost of filling containers.